Defensive publication

ABSTRACT

CHLOROPRENE IS PREPARED IN HIGH YIELDS AND WITHOUT THE FORMATION OF BRINE BY REACTING 3,4-DICHLORO-1-BUTENE WITH CESIUM FLUORIDE, POTASSIUM FLUORIDE, AN ORGANIC QUATERNARY AMMONIUM FLUORIDE, A MIXTURE OF CESIUM FLUORIDE AND POTASSIUM FLUORIDE, OR A MIXTURE OF CESIUM FLORIDE AND SODIUM FLUORIDE, SAID REACTION BEING CONDUCTED IN AN APROTIC ORGANIC SOLVENT. IN THE ALTERNATIVE EMBODIMENT OF THIS INVENTION 2,3-DICHLOROBUTADIENE IS SIMILARLY PREPARED FROM 2,3,4-TRICHLORO-BUTENE OR MESO-1,2,3,4-TETRACHLOEOBUTANE. THE APROTIC SOLVENTS USEFUL IN THIS INVENTION ARE POLAR ORGANIC MATERIALS WHICH ARE LIQUID UNDER THE CONDITIONS OF THE REACTION AND WHICH FORM A HOMOGENOUS PHASE WITH THE ORGANIC CHLORINE-CONTAINING STARTING MATERIAL. THE FLUORIDE ARE ONLY SLIGHTLY SOLUBLE IN THE SOLVENT, BUT THE SOLVENT SHOULD BE ONE WHICH IS CAPABLE OF EFFECTIVELY SOLVATING THE CATION WHILE LEAVING THE FLUORIDE ION UNSOLVATED IN SOLUTION. HYDROGEN-BONDING SOLVENTS, SUCH AS WATER AND THE ALCOHOLS, ARE INEFFECTIVE. SUITABLE SOLVENTS INCLUDE, FOR EXMAPLE, ALIPHATIC CARBOXYLIC ACID AMIDES, ALIPHATIC SULFONES AND SULFOXIDES, AND HEXAALKYL PHOSPHORIC TRIAMIDES. THE TEMPERATURE OF THE REACTION IS CONVENIENTLY FROM ABOUT 25*C. UP TO ABOUT 150*C. IM GENERAL, THE PREFERRED RANGE IS ABOUT 50* TO ABOUT 125* C. TEMPERATURES OF AROUND 90* TO ABOUT 110*C. ARE USUALLY MOST SATISFACTORY.

DEFENSWE PUBLlGATlQN UNITED STATES PATENT OFFICE Published at the request of the applicant or owner in accordance with the Notice of Dec. 16, 1969, 869 0.6. 687. The abstracts of Defensive Publication applications are identified by distinctly numbered series and are arranged chronologically. The heading of each abstract indicates the number of pages of specification, including claims and sheets of drawings contained in the application as originally filed. The files of these applications are available to the public for inspection and reproduction may be purchased for 30 cents a sheet.

Defensive Publication applications have not been examined as to the merits of alleged invention. The Patent Ofllce makes no assertion as to the novelty of the disclosed subject matter.

PUBLISHED MAY 7, 1974 T922,005 FLUORIDE SALTS AS DEHYDROCHLORINATING AGENTS IN THE PREPARATION OF CHLORO- PRENE QR 2,3-DICHLORO-1,3-BUTADIENE Paul Clayton Briggs, Jr., Wilmington, Del., assignor to E. I. du Pont de Nemours and Company, Wilmington,

Del.

Filed Nov. 28, 1973, Ser. No. 419,892 Int. Cl. C07c 21/20 U.S. Cl. 260655 No Drawing. 13 Pages Specification Chloroprcne is prepared in high yields and Without the formation of brine by reacting 3,4-dichloro-1-butene with cesium fluoride, potassium fluoride, an organic quaternary ammonium fluoride, a mixture of cesium fluoride and potassium fluoride, or a mixture of cesium fluoride and sodium fluoride, said reaction being conducted in an aprotic organic solvent.

In the alternative embodiment of this invention 2,3-dichlorobutadicne is similarly prepared from 2,3,4-trichloro-l-butene or meso-1,2,3,4-tctrachlorobutane.

The aprotic solvents useful in this invention are polar organic materials which are liquid under the conditions of the reaction and which form a homogeneous phase with the organic chlorine-containing starting material. The fluorides are only slightly soluble in the solvent, but the solvent should be one which is capable of effectively solvatlng the cation while leaving the fluoride ion unsolvated in solution. Hydrogen-bonding solvents, such as water and the alcohols, are ineffective.

Suitable solvents include, for example, aliphatic carboxylic acid amides, aliphatic sulfones and sulfoxides, and hexaalkyl phosphoric triamidcs.

The temperature of the reaction is conveniently from about 25 C. up to about 150 C. In general, the preferred range is about to about 125 C. Temperatures of around to about C. are usually most satisfactory. 

